MKAbeFook for Facebook. Uses the WebKit browser with asynchronous requests, photo uploads, and much more. It can call any API method and returns the result in standard Cocoa types. It is distributed under a BSD style license.
WalmartLabs has released OneOps, a cloud management and application lifecycle management platform, as open source. OneOps is a multi-cloud application orchestrator that developers can use to quickly develop and launch applications as well as maintain them throughout the entire application lifecycle.
The Swipp API allows developers to integrate Swipp's "Social Intelligence" into their sites and applications. Public information is not available on the API; interested parties are asked to email firstname.lastname@example.org. Once available the APIs will "make it possible for people to interact around any topic imaginable."
What happens when the API is technically secure but the environment, whether widget, web site or mashup, is not? Recent security breaches in MySpace and Yahoo, which led to the release of semi-embarrassing photos of prolific celebs Paris Hilton and Lindsay Lohan, points out the added opportunities for hackers in the open web.